During open heart surgery blood drains into the left ventricle of the heart. This may cause distention of the left ventricle, which may cause complications during open heart procedures. Therefore, it is advantageous to drain blood from the left ventricle through the use of a suction or vacuum pump and associated extracorporeal tubing. Problems associated with left ventricle drainage include the use of excessive suction, a buildup of pressure in the drain line itself, and reverse blood flow to the heart. These problems may complicate the open heart surgery.
In order to alleviate such problems arising from left ventricle drainage, extracorporeal circuits are employed both to control the amount of pressure in the drainage line and to prevent distention of the left ventricle. These circuits typically include check and relief valves, which prevent flow towards the heart, while allowing flow only away from the heart. A vent in the valve body minimizes excessive vacuum upstream from the valve. The valve allows excessive downstream pressure to be vented as well. Thus, the valve has the dual relief functions of both limiting excessive vacuum as well as controlling the amount of pressure in the downstream line.
Previously valves placed in the drainage circuit such as those in U.S. Pat. Nos. 4,671,786; 4,758,224; 4,725,266; and 4,502,502 have employed various venting and vacuum-control methods, sometimes resulting in complicated and cumbersome valves. Such valves contain several elements, including umbrella valves, duckbill valves, or a combination thereof. However, these combinations have often been elaborate, increasing the risk of failure during the operation. Complicated valve structures often lead to an increase in surface area of the flow path, which may foster a risk of undue blood coagulation in the device. This, in turn, increases the risk of occluding the valve. Furthermore, numerous and complicated venting paths also increase the risk of contamination of the blood.
In addition, the known valves are fairly expensive to produce given the intricate nature of their structure.
In order to alleviate potential pitfalls of previous valves in the art, a simpler and more reliable left ventricular relief valve that is relatively inexpensive to manufacture is needed.